Power MOS transistors are the most commonly used power electronic elements in power conversion devices. In order to reduce the power transistor switching loss of the power conversion device, a faster power transistor is proposed. In order to achieve better conversion efficiency, generally, the driving resistance of the power transistor may be adjusted, the resistance value of the driving resistor may be lowered, and the driving current may be increased, so as to achieve smaller switching loss, and elevate the efficiency of the conversion device.
However, the negative effect of increasing the power transistor conduction time and elevating the power transistor conducting speed is that the surge of the secondary side power element of the conversion device may increase at the time of cutoff, and the surge voltage may increase significantly with the increase of the input voltage of the conversion device, even exceeding the rated voltage of the power transistor itself, in addition, the surge voltage may cause the electromagnetic interference which reduces the efficiency of the power conversion device.
Therefore, how to control the driving capability of the power transistor effectively, elevate the efficiency of the power conversion device, and lower the electromagnetic interference, are problems to be improved in the field.